A male sterility gene homolog, designated BcMS2, was isolated from flower buds using gene-specific primer pairs and was submitted to GenBank under accession number EF093533. Comparison of BcMS2 gene with MS2 from Arabidopsis thaliana and MS2Bnap from Brassica napus revealed some differences in gene structure and evolution. The full genomic DNA sequence of BcMS2 was 2,576 bp in length containing 8 exons and 7 introns, more than those of MS2Bnap but less than MS2. RT-PCR showed that BcMS2 gene expressed only in stage III flower buds of male fertile Chinese cabbage-pak-choi 'ZUBajh97-01B' and there were no detection in all organs of Polima cytoplasmic male sterility (CMS) line 'Bpol97-05A' and Ogura CMS line 'Bogu97-06A'. Furthermore, RT-PCR revealed that BcMS2 expressed only in anthers of male fertile material and there were no expression in sepals, petals, filaments and pistils. These results suggested that BcMS2 was an anther-specific gene and might be essential for the fertility of Chinese cabbage-pak-choi.